1. Field of the Invention
The invention relates to protective coating compositions for application to surfaces subject to contact with airborne paints wherein said composition is washable from the surfaces and is used to protect the surfaces from contact with the airborne paint. 2. Description of the Prior Art
The manufacture of many articles requires the application of a spray coating of a paint upon exposed surfaces. Typically, such articles include consumer and industrial articles such as automobiles, automobile panels and parts, appliances, machinery, and the like.
For the application of the sprayed paint to such articles, it is well known to the art to use a "spray booth". Generally, a spray booth comprises a sealable chamber which is large enough to hold the article upon which the sprayed paint is to be applied. The article is placed therein, the chamber closed and then by means by human operators operating pressurized spray guns and/or through the use of robotic operators operating spray guns or spray nozzles, a desired coat of paint may be applied to the exposed surfaces of the article. The spray booth functions to retain any sprayed paint which may be "oversprayed" and does not adhere to the article, which oversprayed paint is entrained in the air, thus becoming "airborne", within the spray booth and which may ultimately deposit upon a surface within the spray booth other than the surface of the article. The spray booth may be seen to act as an isolation chamber isolating the air within the spray booth from the exterior environment.
One shortcoming in the use of spray booths is that due to the nature of the spray painting operations carried therein, it is very difficult to control or to limit the surfaces upon which the sprayed paint may ultimately come to rest. As such, the paint which is desirably sprayed only upon the article is deposited not only on the article being sprayed, but also upon any exposed surface within the sprayed booth. Such surfaces include the walls, ceiling, any gratings, the operators themselves, and any equipment or apparatus within the spray booth. This is highly undesirable as during possible subsequent applications of different types of sprays or different colors of sprays, there was a risk of contamination from a prior applied sprayed paint, and as such a possible distraction from the appearance of the article being painted. Further, consequent to the fact that many paints which are used in such spray painting operation contain volatile organics their possible health risk to human operators who operate within the confines of the spray booth, it is desirable to maintain cleanliness within the spray booth particularly of paint deposited upon surfaces in the spray booth and thereby limit the exposure of human operators to these volatile organics.
Various methods are presently known to the art for limiting the retention of over sprayed paint within the spray booth. One such method referred to as a "water curtain" method finds us in protecting the vertical walls of the spray booth. In such a method, a thin laminar film of water constantly flows from the top edge and the bottom edge of the spray booth walls; thereby, limiting the contact of any entrained paint in the air with the wall surfaces. While this method is known and highly effective in limiting the deposition of the wall surfaces, it nonetheless limited only to wall surfaces and cannot be used for example upon the ceilings, floors, or in covering the equipment and apparatus contained within the spray booth.
Coating compositions comprising acrylics which are used to coat surfaces within the spray booth prior to the application of a sprayed paint to an article are also known to the art. One such acrylic is a pigmented acrylic which may be applied to exposed surfaces which are desirably protected. The pigmented acrylic provides an effective coating against entrained paint, however, it itself is not readily removable from the surfaces upon which it is applied. A further acrylic coating known to the art is a clear acrylic coating composition which may, in a similar manner to the pigmented acrylic noted, may be applied to surfaces within the spray booth. The clear acrylic provides the benefit of non-discoloration of the surfaces within the spray booth. However, is slippery and is known to have poor resistance to a wide variety of organic solvents which find common use as constituents in spray painting compositions. Both of these acrylic containing compounds are also known to comprise a proportion of volatile organic constituents, which, while effective in forming these acrylic comprising compositions also provide a further supplemental health hazard to human operators operating within the spray booth.
Therefore, it is apparent that there is a continuing need in the art for further improved compositions for protective coatings which may be readily applied to surfaces which are subject to contact with airborne paints, wherein such coating composition is readily washable, has little or no volatile organics within its composition, and which does not discolor the surfaces upon which it is applied.